In applicants' U.S. Pat. No. 5,431,551, there is disclosed and claimed a rotary device comprised of a housing comprising a curved inner surface with a profile equidistant from a trochoidal curve, an eccentric mounted on a shaft disposed within said first housing, a first rotor mounted on said eccentric shaft which is comprised of a first side, a second side, and a third side, a first partial bore disposed at the intersection of said first side and said second side, a second partial bore disposed at the intersection of said second side and said third side, a third partial bore disposed at the intersection of said third side and said first side, a first solid roller disposed and rotatably mounted within said first solid bore, a second solid roller disposed and rotatably mounted within said second partial bore, and a third solid roller disposed and rotatably mounted within said third partial bore. The rotor is comprised of a front face, a back face, a first side, a second side, and a third side, wherein a first opening is formed between and communicates between said front face and said first side, a second opening is formed between and communicates between said back face and said first side, wherein each of said first opening and said second opening is substantially equidistant and symmetrical between said first partial bore and said second partial bore, a third opening is formed between and communicates between said front face and said second side, a fourth opening is formed between and communicates between said back face and said second side, wherein each of said third opening and said fourth opening is substantially equidistant and symmetrical between said second partial bore and said third partial bore, a fifth opening is formed between and communicates between said front face and said third side, and a sixth opening is formed between and communicates between said back face and said third side, wherein each of said fifth opening and said sixth opening is substantially equidistant and symmetrical between said third partial bore and said first partial bore. Each of said first partial bore, said second partial bore, and said third partial bore is comprised of a centerpoint which, as said rotary device rotates, moves along said trochoidal cure. Each of said first opening, said second opening, said third opening, said fourth opening, said fifth opening, and said sixth opening has a substantially U-shaped cross-sectional shape defined by a first linear side, a second linear side, and an arcuate section joining said first linear side and said second linear side, wherein said first linear side and said second linear side are disposed with respect to each other at an angle of less than ninety degrees, and said substantially U-shaped cross-sectional shape has a depth which is at least equal to its width. The diameter is said first solid roller is equal to the diameter of said second solid roller, and the diameter of said second solid roller is equal to the diameter of said third solid roller. The widths of each of said first opening said second opening, said third opening, said fourth opening, said fifth opening, and said sixth opening are substantially the same, and the width of each of said openings is less than the diameter of said first solid roller. Each of said first side, said second side, and said third side has substantially the same geometry and size and is a composite shape comprised of a first section and a second section, wherein said first section has a shape which is different from said second section.
The entire disclosure of this U.S. Pat. No. 5,431,551, and its drawings and claims, are hereby incorporated by reference into this specification. It is noteworthy that the device of this prior patent requires the presence of ". . . a first solid roller . . . ," " . . . a second solid roller . . . ," and ". . . a third solid roller . . ." In an amendment filed in patent application U.S. Ser. No. 079,152, an argument was advanced that "Even if it be assumed . . . that it would have been obvious to modify the structure of Hoffmann in the manner suggested by the Examiner, the modified structure . . . would not produce a structure comprised of solid rollers, as required by applicants' claims."
Applicants have discovered that the use of such solid rollers in the device of U.S. Pat. No. 5,431,551 causes a substantial amount of wear housing.
It is an object of this invention to provide an improved rotary positive displacement device which is as effective as the device of U.S. Pat. No. 5,431,551 but is more durable.
It is an object of this invention to provide an improved rotary positive displacement device which has a lower polar moment of inertia than does the device of U.S. Pat. No. 5,431,551.